Image display surfaces in image display devices such as liquid crystal displays (LCDs) or cathode ray tube display devices (CRTs) are required to reduce the reflection of light applied from an external light source and thus enhance the visibility of the image. To meet this demand, it is common practice to utilize an optical laminate comprising an anti-dazzling layer or anti-reflection layer provided on a light transparent base material (for example, an anti-reflective laminate) and thus to reduce the reflection of light frorri an image display surface in the image display device, whereby the visibility of the image is improved.
In an optical laminate comprising layers with a large refractive index difference stacked on top of each other, however, interface reflection and interference fringes often occur at the interface of the mutually superimposed layers. In particular, when black is reproduced on an image display surface in a screen display device, the occurrence of interference fringes is significant, resulting in lowered image visibility. Further, in this case, the appearance of the image display surface is deteriorated. In particular, interference fringes are likely to occur when the refractive index of the light transparent base material and the refractive index of the hardcoat layer are different from each other.
On the other hand, Japanese Patent Laid-Open No. 75605/2003 proposes an antireflection hardcoat sheet comprising a transparent base material film and, provided on the transparent base material film in the following order, an intermediate-refractive index layer having a refractive index of 1.5 to 1.7, a higher-refractive index layer having a refractive index of 1.6 to 1.8, and further a lower-refractive index layer formed of a material having a lower refractive index than the higher-refractive index layer stacked. The advantage of this antireflection hardcoat sheet is to eliminate the interface reflection, interference fringes and the like. This prior art technique has been accomplished by focusing on the materials that constitute each layer. Further, Japanese Patent Laid-Open No. 205563/2003 proposes a method in which a hardcoat layer is formed on a base material by using a resin containing a solvent capable of dissolving the base material.
To date, there is no prior art recognition that interface reflection and interference fringes can be effectively prevented by forming a thin layer using a resin having specific properties before forming a hardcoat layer on the light transparent base material to improve the state of the interface between the light transparent base material and the hardcoat layer.